import _ from "lodash";

var GPS = {
  PI : 3.14159265358979324,
  x_pi : 3.14159265358979324 * 3000.0 / 180.0,
  delta : function (lat, lon) {
    // Krasovsky 1940
    //
    // a = 6378245.0, 1/f = 298.3
    // b = a * (1 - f)
    // ee = (a^2 - b^2) / a^2;
    var a = 6378245.0; //  a: 卫星椭球坐标投影到平面地图坐标系的投影因子。
    var ee = 0.00669342162296594323; //  ee: 椭球的偏心率。
    var dLat = this.transformLat(lon - 105.0, lat - 35.0);
    var dLon = this.transformLon(lon - 105.0, lat - 35.0);
    var radLat = lat / 180.0 * this.PI;
    var magic = Math.sin(radLat);
    magic = 1 - ee * magic * magic;
    var sqrtMagic = Math.sqrt(magic);
    dLat = (dLat * 180.0) / ((a * (1 - ee)) / (magic * sqrtMagic) * this.PI);
    dLon = (dLon * 180.0) / (a / sqrtMagic * Math.cos(radLat) * this.PI);
    return {'lat': dLat, 'lon': dLon};
  },

  //WGS-84 to GCJ-02
  gcj_encrypt : function (wgsLat, wgsLon) {
    if (this.outOfChina(wgsLat, wgsLon))
      return {'lat': wgsLat, 'lon': wgsLon};

    var d = this.delta(wgsLat, wgsLon);
    return {'lat' : wgsLat + d.lat,'lon' : wgsLon + d.lon};
  },
  //GCJ-02 to WGS-84
  gcj_decrypt : function (gcjLat, gcjLon) {
    if (this.outOfChina(gcjLat, gcjLon))
      return {'lat': gcjLat, 'lon': gcjLon};

    var d = this.delta(gcjLat, gcjLon);
    return {'lat': gcjLat - d.lat, 'lon': gcjLon - d.lon};
  },
  //GCJ-02 to WGS-84 exactly
  gcj_decrypt_exact : function (gcjLat, gcjLon) {
    var initDelta = 0.01;
    var threshold = 0.000000001;
    var dLat = initDelta, dLon = initDelta;
    var mLat = gcjLat - dLat, mLon = gcjLon - dLon;
    var pLat = gcjLat + dLat, pLon = gcjLon + dLon;
    var wgsLat, wgsLon, i = 0;
    while (1) {
      wgsLat = (mLat + pLat) / 2;
      wgsLon = (mLon + pLon) / 2;
      var tmp = this.gcj_encrypt(wgsLat, wgsLon)
      dLat = tmp.lat - gcjLat;
      dLon = tmp.lon - gcjLon;
      if ((Math.abs(dLat) < threshold) && (Math.abs(dLon) < threshold))
        break;

      if (dLat > 0) pLat = wgsLat; else mLat = wgsLat;
      if (dLon > 0) pLon = wgsLon; else mLon = wgsLon;

      if (++i > 10000) break;
    }
    //console.log(i);
    return {'lat': wgsLat, 'lon': wgsLon};
  },
  //GCJ-02 to BD-09
  bd_encrypt : function (gcjLat, gcjLon) {
    var x = gcjLon, y = gcjLat;
    var z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * this.x_pi);
    var theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * this.x_pi);
    var bdLon = z * Math.cos(theta) + 0.0065;
    var bdLat = z * Math.sin(theta) + 0.006;
    return {'lat' : bdLat,'lon' : bdLon};
  },
  //BD-09 to GCJ-02
  bd_decrypt : function (bdLat, bdLon) {
    var x = bdLon - 0.0065, y = bdLat - 0.006;
    var z = Math.sqrt(x * x + y * y) - 0.00002 * Math.sin(y * this.x_pi);
    var theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * this.x_pi);
    var gcjLon = z * Math.cos(theta);
    var gcjLat = z * Math.sin(theta);
    return {'lat' : gcjLat, 'lon' : gcjLon};
  },
  //WGS-84 to Web mercator
  //mercatorLat -> y mercatorLon -> x
  mercator_encrypt : function(wgsLat, wgsLon) {
    var x = wgsLon * 20037508.34 / 180.;
    var y = Math.log(Math.tan((90. + wgsLat) * this.PI / 360.)) / (this.PI / 180.);
    y = y * 20037508.34 / 180.;
    return {'lat' : y, 'lon' : x};
    /*
     if ((Math.abs(wgsLon) > 180 || Math.abs(wgsLat) > 90))
     return null;
     var x = 6378137.0 * wgsLon * 0.017453292519943295;
     var a = wgsLat * 0.017453292519943295;
     var y = 3189068.5 * Math.log((1.0 + Math.sin(a)) / (1.0 - Math.sin(a)));
     return {'lat' : y, 'lon' : x};
     //*/
  },
  // Web mercator to WGS-84
  // mercatorLat -> y mercatorLon -> x
  mercator_decrypt : function(mercatorLat, mercatorLon) {
    var x = mercatorLon / 20037508.34 * 180.;
    var y = mercatorLat / 20037508.34 * 180.;
    y = 180 / this.PI * (2 * Math.atan(Math.exp(y * this.PI / 180.)) - this.PI / 2);
    return {'lat' : y, 'lon' : x};
    /*
     if (Math.abs(mercatorLon) < 180 && Math.abs(mercatorLat) < 90)
     return null;
     if ((Math.abs(mercatorLon) > 20037508.3427892) || (Math.abs(mercatorLat) > 20037508.3427892))
     return null;
     var a = mercatorLon / 6378137.0 * 57.295779513082323;
     var x = a - (Math.floor(((a + 180.0) / 360.0)) * 360.0);
     var y = (1.5707963267948966 - (2.0 * Math.atan(Math.exp((-1.0 * mercatorLat) / 6378137.0)))) * 57.295779513082323;
     return {'lat' : y, 'lon' : x};
     //*/
  },
  // two point's distance
  distance : function (latA, lonA, latB, lonB) {
    var earthR = 6371000.;
    var x = Math.cos(latA * this.PI / 180.) * Math.cos(latB * this.PI / 180.) * Math.cos((lonA - lonB) * this.PI / 180);
    var y = Math.sin(latA * this.PI / 180.) * Math.sin(latB * this.PI / 180.);
    var s = x + y;
    if (s > 1) s = 1;
    if (s < -1) s = -1;
    var alpha = Math.acos(s);
    var distance = alpha * earthR;
    return distance;
  },
  outOfChina : function (lat, lon) {
    if (lon < 72.004 || lon > 137.8347)
      return true;
    if (lat < 0.8293 || lat > 55.8271)
      return true;
    return false;
  },
  transformLat : function (x, y) {
    var ret = -100.0 + 2.0 * x + 3.0 * y + 0.2 * y * y + 0.1 * x * y + 0.2 * Math.sqrt(Math.abs(x));
    ret += (20.0 * Math.sin(6.0 * x * this.PI) + 20.0 * Math.sin(2.0 * x * this.PI)) * 2.0 / 3.0;
    ret += (20.0 * Math.sin(y * this.PI) + 40.0 * Math.sin(y / 3.0 * this.PI)) * 2.0 / 3.0;
    ret += (160.0 * Math.sin(y / 12.0 * this.PI) + 320 * Math.sin(y * this.PI / 30.0)) * 2.0 / 3.0;
    return ret;
  },
  transformLon : function (x, y) {
    var ret = 300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * Math.sqrt(Math.abs(x));
    ret += (20.0 * Math.sin(6.0 * x * this.PI) + 20.0 * Math.sin(2.0 * x * this.PI)) * 2.0 / 3.0;
    ret += (20.0 * Math.sin(x * this.PI) + 40.0 * Math.sin(x / 3.0 * this.PI)) * 2.0 / 3.0;
    ret += (150.0 * Math.sin(x / 12.0 * this.PI) + 300.0 * Math.sin(x / 30.0 * this.PI)) * 2.0 / 3.0;
    return ret;
  }
};

class WxLocation {

  /**
   * 获取当前位置
   */
  getLocation () {
    return new Promise((resolve, reject) => {
      window.wx.getLocation({
        type: 'wgs84', // 默认为wgs84的gps坐标，如果要返回直接给openLocation用的火星坐标，可传入'gcj02'
        success: function (res) {
          var latitude = res.latitude; // 纬度，浮点数，范围为90 ~ -90
          var longitude = res.longitude; // 经度，浮点数，范围为180 ~ -180。
          var speed = res.speed; // 速度，以米/每秒计
          var accuracy = res.accuracy; // 位置精度

          console.log("当前地理位置:", latitude, longitude);

          resolve({
            latitude,
            longitude,
          });
        }
      });
    });
  }

  openLocation(lng, lat, name, address, callback) {
    let gps = GPS.bd_decrypt(lat, lng);

    wx.openLocation({
      type: "gcj02",
      latitude: gps.lat, // 纬度，浮点数，范围为90 ~ -90
      longitude: gps.lon, // 经度，浮点数，范围为180 ~ -180。
      name: name, // 位置名
      address: address, // 地址详情说明
      scale: 14, // 地图缩放级别,整形值,范围从1~28。默认为最大
      // infoUrl: '' // 在查看位置界面底部显示的超链接,可点击跳转
    });

    //do not callback.
  }
}

export default WxLocation;

